Rotary machine



Nov. 12, 1935. R. T.' KNAPP 2,020,611

ROTARY MACHINE Filed Jan. 16, 1935 4 Sheets-Sheet 1 INENTOR. Eggaer 771L501 KNHPP M, m with? ATTORNEYS.

ROTARY MACHI NE Filed Jan. 16, 1 4 Sheets-Sheet 2 INVENTOR. ROBE/2T 721L507 KNAPP ATTORNEYS.

R. T. KNAPP ROTARY MACHINE Nov. 12, 1935.

Filed Jan. 16, 1955 4 Sheets-Sheet 5 ATTORNEYS.

Nov. 12, 1935. R. T. KNAPP 2,020,611

ROTARY MACHINE Filed Jan. 16, 1935 4 SheetsSheet 4 jifilE.

- INVENTOR. ROBE/an- 121L507" KVAPF BY M J06.

ATTOR NE Y5.

' practicable.

Patented Nov. 12, 1935 UNITED STATES PATENT OFFICE ROTARY MACHINE Application January 16, 1935, Serial No. 2,121

13 Claims.

This invention relates generally to positive displacement rotary machines.

An object of the invention is to provide a rotary I machine in which the volume of medium passed will remain constant for any given speed.

It is generally recognized that in rotary machines regardless of the type of impellers employed, the amount of slippage of the medium between the impellers and the casing determines the efiiciency of such machines. In rotary machines of the multi-vane type, it has never been possible to keep the clearances sufiiciently close at the effective sealing lines to enable them to be commercially successful as the volumetric efficiency could not be held constant and of a relatively high value per revolution, nor has it been possible to operate such machines at high speeds with any degree of success. It is a broad object of the present invention to overcome these heretofore existing inaccuracies and provide a machine of the multi-vane type, the accuracy of operation of which can be depended upon at all speeds and the operating speed made much higher than has been heretofore considered commercially A machine designed in accordance with the present disclosure can be used for many commercial purposes or whereand whenever it is desired that the amount of medium passed shall be held constant at any given speed.

The invention is particularly directed to the type of rotary machine employing laterally reciprocal cam actuated vanes which also have movement relative to the annular wall of a stator, and. an important object is to provide positive means for providing close clearances between the stator wall and the periphery of the rotor at the slots of the rotor or where the cams contact the wall and good and sufficient side clearances between the vanes and the cams, thus making it possible to decrease leakage losses to a very small amount and insuring that the volumetric efliciency will remain quite high and constant per revolution.

Another important feature finds expression in the novel forms of cams and vanes employed and their relationship to each other to automatically compensate for wear upon the contact surfaces and thus insure constant maintenance of the aforestated close clearances.

Another object resides in the novel forms and arrangements of cams and vanes, whereby the aforementioned automatic wear compensating feature will be made entirely effective and reliable over long operating periods of time.

Another object is to provide in an organization of the class stated, coacting instrumentalities which function .to insure operative maintenance of the intended clearances because of the shapes of said instrumentalities and their relationship I to each other, assisted only by centrifugal force when the machine is operating.

A further object is to provide a machine which will be smoother in action and better balanced than was possible heretofore and, therefore, de- 10 void of excessive vibration at high speeds.

Another object is to provide a machine in which the principal wear will be upon the vanes and not upon more expensive parts of the machine, which vanes, when worn beyond practical use, can be 15 readily removed and new vanes substituted therefor at small cost.

In the accompanying drawings,

Figure 1 is a view in horizontal section through the machine with parts in full lines and parts 20 broken away for the purpose of clearness;

Figure 2 is a perspective view of one of the stator and plates and cam;

Figure 3 is a perspective view of the complementary stator and plate and cam;

Figure 4 is a perspective view of the rotor;

Figure 5 is a perspective view in top plan of the machine with the stator body in section;

Figure 6 is a perspective view of the stator body; 30 Figure 7 is a view in top plan of the machine with parts broken away and parts in section to clearlycdisclose the fluid intake and discharge ports;

Figure 8 is a perspective view of one of the complete vane assemblies;

Figure 9 is a vertical longitudinal section through the machine showing a part of the rotor broken away to clearly disclose the sizes of the port areas and the location thereof relative to the co-operable cam surfaces;

Figure 10 is a section taken substantially on the line l0-l0 of Figure 9;

Figure 11 is a view in elevation of one of the cams showing schematically the relationship of the vanes to the ports during a part of the cycle of the rotor;

Figure 12 is a vertical section through a slightly different form of the invention;

Figure 13 is a view partly in top plan and partly in horizontal section of another form of the invention, and

Figures 14 and 15 are views in elevation of further forms of vanes that can be employed.

The term rotary machine shall be broadly construed to include 1) machines designed for use as hydraulic motors for transferring energy stored in a liquid under pressure into mechanical energy of rotation and without requiring substantial alteration from the form of construction shown herein; (2) machines for compressing gas or for use as gas motors; (3) machines for pumping liquids, such as oil or water; (4) machines in which the volumetric efficiency is intended to be consistently very high as is required for metering purposes in manufacturing processes where the pressure rise shall be held at a constant value.

The machine comprises a stator or casing l5 having an annular vane contacting surface l5a, the ends of which casing are closed by removable heads or plates |6|6, on the inner face of each of which is a circular vane guiding cam l1. Concentrically mounted in the casing and disposed between the cams is a rotor 8 in which vanes I9 are mounted for lateral reciprocation and to move linearly relative to the surface l5a. These parts will now be separately described and the relationship of one part to another fully set forth to the end that a clear and comprehensive understanding of the functional advantages of the machine will be readily apparent to persons skilled in the art to which the invention relates.

The stator or casing I5 comprises a hollow body, the openings in the end of which are sealed by the aforementioned end plates Hi. The inner concentric wall 2| of the stator is of the same diameter throughout and is spaced apart from the outer wall 22 of said stator to provide an inintervening chamber 23 between said walls, at the diametrically opposite sides of which are inlet and outlet pipes 24 and 25, respectively. The chamber is divided by fins 26 to provide separate compartments or spaces 21 and 28, the former communicating with the intake pipe 24 and respective intake ports 29-29 in said wall 2|. In like manner, the space 28 communicates with the out let pipe 25 and respective discharge ports 3030 in said wall 2 I. It thus follows that medium entering the chamber 23 by way of the pipe 24 can be continuously conducted from the ports 29 to the discharge ports 30, thence to the outlet side 25 of the stator. It is, of course, understood that the capacity areas of the intake and discharge pipes 24 and 25 are in operative proportion to the capacity of the machine.

It will be noted that the intake and discharge ports 29 and 30 are disposed in relationship to each other so that the port 29 of one pair is diametrically opposite the port 30 of the other pair. It will also be observed that the inner face of the wall 2| lies wholly parallel to the axis of the stator about which the rotor |8 revolves and that the axial spacing of the ports 29 and 3|l| of each pair employed is so calculated as to dispose these ports in positions which are lateral relative to the face width of the rotor. These ports are all of the same length and are of corresponding areas and, therefore. of equal capacities, whereby the amount of conveyed medium and displacement thereof will be equal and constant and of the full capacity of the machine per revolution of the rotor. panying drawings, the ports 29 and 30 are each equal in length to one fourth the circumference of the circle described by the inner surface of the stator wall 2| and concentric to the axis of the rotor, the purpose of which will be explained presently.

The identical circular vane guiding cams I! In Figure 6 of the accomv are each generated by a trapezoidal plane, the longer parallel edge of which coincides with the generating axis and slides axially as the plane rotates. In this manner, the cams remain invariant in respect to each other so that the cross section of the space between them taken upon a plane containing the axis is identical in shape with all similar cross sections on all planes entering the axis. Cams constructed as aforementioned are provided with diametrically opposite 1o abutments 32 and 33 of equal face areas, positioned at respectively different axial distances relative to the sides of the rotor confronting same and said abutments will thus be formed with curved portions 34 and 35 which are also 15 of equal face areas.

Said cams are mounted with a relative angular displacement of 180 so that the axial distance between them is constant and equal to the effective vane width, and it will be appre- 20 ciated on reference to Figure 1 of the drawings that the radial distance between the inner and outer circles of each cam is equal to the length of the oblique edge of the vane at allplaces in the cycle of the rotor, so that the wear upon 25 the rubbing or contact surfaces will be equal and constant at all times, that is to say, due to the fact that the vanes are quadrilaterals of trapezoidal form in which the equal length edges are always parallel to the rubbing or contact surfaces 0 of the cams and the short edges thereof are always parallel to the inner surface of the annular wall 2| of the stator, the radial thrust upon said surfaces will be greatly reduced'as compared with machines of the prior art, and the wear upon all contact surfaces thereby made more nearly equal along all rectilinear sealing lines.

Extending radially through the cams and under the respective surfaces 34 and 35 thereof are intake and outlet ports 36 and 31 which are 00- 40 incident with the corresponding ports 29 and 30 in the stator wall 2| and of equal length therewith. These ports 36 and 31 communicate directly with portways 31a and 38 in said surfaces 34 and 35 and, as shown, the centers of the port- 45 ways 38 are coincident with the lines of joinder between the curves 34 and the high abutments 33, thus insuring complete displacement of the medium at the discharge ports of the machine.

The rotor I8 consists of a solid cylindrical body 50 concentrically mounted in the stator and having a hub 39 splined at 40 to a shaft 4|. The diameter of said body is such in proportion to the internal diameter of the annular wall 2| of the stator as to insure a close peripheral clearance 55 between these parts. The body is provided with radial slots 42 of which there are four in the present embodiment of the invention, and same are arranged in diametrically opposite pairs. This is because the cams of the machine are 6 mounted as aforestated with a relative angular vane displacement of 180 and with an axial dis tance between them that is constant and equal to the effective vane width.

The rotor body is formed with conical sides 43, 65 each of which is generated by the rotation of a straight line round the axis of the rotor from which it is at a constant distance and to which it is inclined at a constant angle which is oblique to said axis and parallel to all rubbing or con- 70 tact surfaces of the cam which confronts it. It, therefore follows that said sides are in constant sealed contact with the high abutments with only a very scant clearance between them.

The hub 39 is provided at its respective sides with co-axial extensions 44, the same having angular faces 45, and as illustrated, the hub is formed with grooves 46 which terminate at said faces, thus enabling the vanes to slide axially relative to the cams |1|1 and also enabling the vanes to move radially in order that their short edges which are parallel to the wall 2| will engage the inner surface of said wall without clearance therebetween and in order also to permit axial movement of the vanes to compensate for wear on the rubbing surfaces. In combination with cams generated as aforestated, it follows that the use of vanes shaped as shown is highly novel and useful as the radial clearance between the rotor periphery at the slots 42 will be kept small and the equal length edges 4949 of the vanes made to coact with both cams along the entire lines of contact.

The vanes I9 each consist of identical quadrilateral lamina: of trapezoidal form, the opposite parallel long and short edges 41 and 48 of which are parallel to the axis of rotation of the rotor. The long edges 48 are disposed at the hub 39 and mounted in the grooves 46 as aforestated. The altitude of each vane is equal to the perpen dicular distance between the bottom wall of the groove in which it is mounted and the inner surface of the annular wall 2| of the stator. The equal length short edges 49-49 are thus parallel to all contact surfaces of the respective cams |1-|1 and the effective width of each cam is thus equal to the axial distance between both cams.

When the rotor is in motion, the vanes will move by centrifugal force a. slight distance radially toward the inner surface of the aforementioned wall 2| and same will be guided by the cams so that the short sides 41 of the vanes will be presented squarely against said surface. Serious wear upon said surface will be prevented because of the obliquity of the active faces of the cams and the corresponding obliquity of the sides 49-49 of said vanes, the same acting to resist the direct eifect of radial force and to apportion said force among the active guiding faces of the stator wall 2|. Wear occurring upon the edges 41 and 49-49 of the vanes will thus be equal at all said edges of the vanes, and the vanes, because of said slight radial movment herein provided for, will adapt themselves to all wear upon the active rubbing edges, thus insuring constant close clearances at all contact or sealing lines. The motion of the vanes will thus be parallel relative to all contact surfaces of the machine and wear upon said surfaces will be consistently even at all operating speeds. In consequence of these forms, shapes and arrangements of the parts, the

machine can be operated at high speed and with an assured volumetric efficiency which will be consistently high.

While vanes consisting of identical lamina are highly desirable in that they will freely move separately and will thereby more easily adapt themselves to the rubbing surfaces of the cams and insure close clearances, I shall not expect to be limited to the use' of such vanes. A vane formed from a single blank of material can be used with excellent .results where the cams are constructed as herein disclosed and the vanes are shaped as described.

The eft hand plate IS in FigurelO is formed with a journal box 50 which is closed by a head Contained in said box is a bushing 52 in which one end of the shaft 4| is received. The bushing 52 is alined with a similar bushing 53 contained in a recess 54 in the bearing extension 55 of the right hand plate |6 (Figure 10.) Said extension 55 is also formed with a stuffing box 55 through which and through the bushing 53 the opposite end of the shaft extends. 55 contains a suitable compressible packing 51 which can be tightly pressed against the circumferential surfaces of the shaft by adjusting the element 58 in a compressing direction. It follows from this construction that the stator will be effectively held against leakage at the heads |6-|6 and around the shaft 4|.

To provide means for preventing serious abrasion of any of the'rubbing surfaces of the machine and for reducing the frictional resistance they oppose to relative motion of the parts, and thus enable maximum benefit to be derived from the power developed during operation of the machine and for also insuring greater durability of the parts employed, use is made of the following system of lubrication: Extending through the fins .6 are one or more orifices 59 adapted to be supplied with a suitable lubricant and con ducted from said orifices to the peripheral face of the rotor and to the space between same and the inner annular surface of the stator wall 2|, thence carried around the entire rotor chamber. Similar orifices 60 extend through the heads I5 and open directly onto the active vane guiding faces .of the cams l1 and the conical 90 sides 43 of the rotor. The several orifices herein referred to can be connected by the pipes 6| with any suitable force feed pump (not shown), whereby a suitable grade of lubricant can be continuously distributed to the parts to be lubri- 95 cated.

The flat angular faces 45 of the hub extensions 44 are in free rubbing contact with like faces 62 at the inner ends of the alined bushings 52 and 53. As these faces are continued into the active faces of the cams |1|1, they too will be adequately lubricated and also will this be true of the shaft 4| and the annular bearing faces 63 of said cams.

I have now fully disclosed and described a positive displacement rotary machine of the doubleacting multi-vane type in which respective high and low pressure chambers are formed at the opposite sides of a single rotor, which chambers, because of the actions of the circular cams I1 and vanes |9, will become completely filled during the inlet part of the cycle, and, in like manner, completely emptied during the discharge part of the cycle. Four vanes are preferably employed and radially mounted on the rotor, and, as shown, the cams are mounted with a relative angular displacement of 180 so that the distance between them is equal to the effective vane width. Each of the surfaces 32, 33, 34 and 35 describes a circular arc of 90 in which the arcs describing the sines 34 and 35 merge into the arcs which describe the diametrically opposite abutments 32 and 33. The effective radial distance from the inner circle of each cam to the outer circle of the cam is the same at all 65 places in the cycle and equal to the length of the side 49 of the vane which the cam contacts, less the wall thickness of the hub 39, the normal altitude of the vane being equal to the distance between the inner wall of the stator and the bottom wall of said hub groove 46. It follows that the .normal clearance between all contact surfaces is, therefore, uniformly close and that each vane is always entirely in contact with both cams and with the annular wall of the stator.

The box 5 Incident to the manner in which the cams are generated, the oblique surfaces thereof, with the annular wall of the stator and the bottom walls of the grooves 46, give to the space between. the cams a trapezoidal shape conforming to the shapes of the vanes and of a width co-extensive with the vane width. Bearing in mind that the vanes are free to move a short distance radially, and are disposed with their equal sides 49-49 in contact with the oblique faces of the cams, radial thrust imposed upon the vanes by centrifugal force will be partly spent against the oblique faces of the opposed cams in directions substantially as represented by the lines ya and ha which are at right angles to said sides of the vanes and said oblique cam faces, thereby greatly relieving the friction from the annular wall of the stator without destroying any of the sealing lines. The cams thus function in the dual capacity of means for guiding the vanes and as thrust surfaces for the equal sides of said vanes, a feature which, to my knowledge, has never before been embodied in rotary machines.

The direction of rotation of the rotor may be either :clockwise or counter-clockwise. In Figure 9, assuming that the machine acts as a pump, the course taken by the medium is indicated by the arrows as regards one side of the machine. The course taken by the medium at the opposite side of the machine will be in an opposite direction. As both sides operate in the same manner, it will be readily apparent that as the medium enters the ports 29 at the low pressure side of the machine, it will be taken into 'the chambers between the respective vanes by induced suction, then discharged from the ports 30 at the high pressure side of the machine. The surfaces 34 and 35 of the cams are co-extensive with the arcs which describe the ports 29 and 30 and are likewise co-extensive with the port spaces 36 and 31. The discharge port 38, which extends into the area of the abutment 33, opens directly into the port space 36. The ports 29, 30, 36, 37, 31a and 38 are very precisely figured so that their combined areas are in operative proportion to the capacity of the machine to thus insure the complete filling of the vane chambers during the suction part of the cycle and in like manner insure the complete emptying of the chambers during the discharge part of the cycle. The volumetric efficiency of a machine constructed in accordance with this disclosure will be consistently high, and at high speed the objectionable vibration heretofore experienced with such type of machines will be eliminated and the discharge capacity held constant.

I stress particularly the forms and constructions of the cams and actuating vanes of the machine and their relation to each other and to the stator to maintain the aforementioned uniform close clearances even after long use and to relative friction due to pressure upon the vanes, whereby to prevent premature injury to the surfaces and so that both the starting load and the running load will be reduced. A machine characterized as set forth will be smooth running .and free of objectionable vibration as means are employed for automatically compensating for wear at the contact surfaces, the volume of fluid or medium displaced will be held constant for any given speed and the durability of the machine will be enhanced.

Where the machine is employed for pumping oil, there will exist no need for additional lubrication of the contact surfaces and the lubricating system first above mentioned can be eliminated. I

I do not claim broadly a rotary machine having vanes operating between co-operable cams and 5 adapted to reciprocate laterally and also move radially, but I do broadly claim in combination with these or functionally similar elements, the use of means for automatically compensating for wear upon the contact surfaces and for distrib- 10 uting the thrust imposed on the vanes so that the wear will be reduced and damage to the contactv surfaces prevented, features which were not possible with machines of the prior art. While I have referred to the use of vanes of specific 15 shapes and have disclosed cams of unique design, I shall claim as my invention earns the effective contact surfaces of which are disposed at an angle of obliquity which is less than to the axis of the rotor, so that confronting sur- 20 faces will converge toward the stator wall with which the sides 41 of the vanes are in parallel contact. I claim also a rotor the contact surfaces of which consist of frusta or zones of complete cones, thereby providing angles of obliquity :5 which are in constant parallel relation to the plane faces of the high abutments 33.

The manner in which the ports of the camsextend partly into the active vane contacting surfaces is also important as by means thereof the so chamber pressures will be satisfactorily relieved during the discharge part of the cycle and a. complete discharge of the medium thereby madepossible.

In Figure 12 of the drawings the vanes I9a are 35,

the same in every material respect as the vanes I9, except that they are each set at an angle to enable their outer edges to follow and effectively sweep the inner surface of the stator wall Zla.

In Figure 13 of the drawings, the vanes lSb 40 function like the vanes [9, except that they are diagonally mounted in the rotor.

In the form shown in Figure 12 the cams are generated substantially as aforestated with respect to the manner of generating the cams I3, 45 it obviously following, however, that the vanes being tangentially mounted, the cams will be generated in consideration thereof so as to provide the necessary parallel contact lines at all places and enable the vanes to compensate themselves 50 to wear upon said surfaces.

In Figure 13, the form therein disclosed will have its cams set for an operative timing of the vane movements and to provide an effective width between the cams which is constant and 55 equal to the vane width.

In Figure 14 of the drawings, the equal length edges of the vane l9c therein illustrated can be concave, while in the form shown in Figure 15, the equal length edges of the vane ltd can be no convex. Such forms of vanes shall of course come within the intention of the invention and scope of the hereto appended claims as the structural and functional equivalents of the form first referred to.

The vanes employed here-in can be constructed of steel of suitable gauge. However, alloys of well known kinds can be substituted therefor or even suitable well known non-metallic compositions of matter having wear resisting qualities.

Several exemplifications illustrating by example the means employed for accomplishing the many objects in view have been fully described and shown herein and it is to be clearly understood that other changes falling within the spirit 1 of the invention and scope of the claims can be resortedto as and when desired. For instance, wherever in the preceding description the term .radial appears as regards the angle at which the vanes of the rotor are set, I shall expectthe scope of the claims to be of such range as to include any one or all of the modifications herein disclosed as well as others which might suggest themselves to persons skilled in the art to which the invention relates. It will broadly suffice to say that whatever may be the angle at which the vanes are set, the cam faces will be generated to conform thereto.

When the vanes are placed substantially at a tangent to the hub of the rotor as shown in Figure 12, the vane receiving slots in said hub can be much deeper than is possible where the vanes are disposed at right angles to the axis of the rotor. In consequence thereof, the vanes can be longer in a direction from the inner parallel edge thereof to the outer parallel edge to thus enable the vanes to be used for a considerably longer period of time, a feature which is highly important and decidedly useful.

What I claim as my invention is:

1. A rotary machine having a casing provided with a rotor chamber having an annular wall; a

=rotor concentrically mounted in the chamber and provided with laterally reciprocal trapezoidal vanes which can also move relative to said annular wall, each vane with its short parallel side confronting said wall and adapted to contact same; and guiding cams for said vanes to axially reciprocate same and enable them to move relative'to said annular wall, said cams each generated by a trapezoidal plane, the longer parallel edge of which coincides with the generating axis and slides axially as the plane rotates, so that the respective cams are invariant relative to each other and so that the cross section of the space between them taken upon a plane containing the axis is identical in shape with all similar cross sections of the vanes.

2. In a rotary machine, the combination with l a pressure chamber having a concentric rotor;

of vanes mounted in the rotor, said vanes being free to move by centrifugal force relative to the chamber surfaces circumferentially of the rotor, the contour of each vane describing a plane figure bounded by four sides in which two thereof are parallel to the axis of the rotor and the remaining two sides angularly related and converging outwardly relative to each other, and cam means having surfaces formed and correlated to the relatively converging vane sides to enable said sides to uniformlyrub thereagainst throughout the lengths of said sides as the vanes move relative to the chamber surfaces in response to centrifugal force and as they move relative to the rotor.

axis of the rotor, and transverse edges, thelatter converging relatively toward the cylindrical wall of the chamber, said end walls of. the chamber provided on their inner faces with cam surfaces converging relativelytoward said cylindrical wall and continuously engaging said transverse edges of said vanes, whereby the vanes are axially reciprocated by said cam surfaces and continuously held outward by centrifugal force against said cylindrical wall to automatically compensate for wear and provide a constant fluid tight seal along all of said aforementioned vane edges.

4. A rotary fluid displacement machine includ- 5 ing a casing having a cylindrical bore and end walls therefor, constituting a fluid displacement chamber; a rotor mounted in said chamber; vanes mounted to slide radially in said rotor and each including two transverse edges relatively converging toward the cylindrical wall of said chamber and one edge disposed parallel to the axis of said chamber, said one edge contacting said cylindrical wall of the chamber; said three edges constituting the only sealing contacts with the casing; and means at the sides of the rotor having surfaces which are angularly complementary to the converging edges of the vanes to automatically maintain constant fluid-tight seals between said aforementioned vane edges and contacting 20.

chamber surfaces. 5. A rotary fluid displacement machine including a casing having a cylindrical bore and end walls therefor, constituting a fluid displacement chamber; a rotor concentrically mounted in said 25 chamber; four-edged fluid displacing vanes mounted in said rotor to slide outwardly relative to the axis of rotation of the rotor and each having an edge disposed parallel to said axis and adapted to be in constant rubbing contact against contact with said two edges and serving to uni- 40 formly maintain said one edge of each vane influid sealed contact with said cylindrical wall of said chamber as the vanes slide outwardly due to wear.

6. In a rotary fluid displacement machine in- 4!},

cluding a casing having a cylindrical bore and end walls therefor, constituting a fluid displacement chamber; a rotor mounted in said chamber and having slots opening respectively onto the periphery and onto opposite ends of the rotor; vanes 50 mounted in said slots and being normally approximately coextensive in a radial direction with the distance between the inner ends of the slots and the cylindrical wall of the chamber, said vanes adapted to slide radially in said slots, the 55- axial extension of each vane being greater than that of the rotor and each vane having two oppositely disposed edges which are angularly related to each other to converge toward the periphery.

of the rotor; and means at the ends of the rotor, 60.

having surfaces which are angularly complementary to the angles of the oppositely disposed edges of the vanes to guide the vanes in their movement radially and prevent chattering of the vanes and for compensating for wear upon the 65 cylindrical chamber wall and upon the surfaces of said means and upon each of the aforementioned vane edges and thereby maintain constant fluid tight seals at said edges as the vanes decrease in size axially and radially in consequence 70 of frictional wear.

7. A fluid displacement machine including a casing having peripheral and end walls constituting a. fluid displacement chamber; a rotor mounted in said chamber; fluid displacing vanes mount- 75 ed in said rotor and slidable relative to the peripheral wall of said chamber and being reciprocable axially of the rotor, each vane having one edge disposed to contact said peripheral wall and transverse edges converging relatively toward said peripheral wall and adapted for alternate projection from the respective ends of said rotor; means for moving said vanes axially for the purpose last stated, said means including surfaces disposed in constant fluid sealing contact with said transverse vane edges and serving also to uniformly maintain said one edge of each vane in fluid sealed contact with said perpiheralwall and 4 thereby maintain fluid tight seals along each of it' walls therefor, constituting a fluid displacement chamber; a rotor concentrically mounted in said chamber; vanes mounted in the rotor to move relative to the cylindrical wall of the chamber and adapted to move axially of the rotor, each vane having an edge disposed parallel to the axis oil the rotor and transverse edges, the latter converging relatively toward said cylindrical wall of the chamber; said end walls of the chamber provided on their inner faces with cam surfaces constantly contacting the transverse edges of the vanes to maintain a directional line of movement of the vanes relative to said cylindrical wall of the chamber which is oblique relative to the line of contact between said cam surfaces and said transverse vane edges, whereby to automatically maintain constant fluid tight seals along the respective aforestated edges of the vanes, said cam surfaces each generated by a plane having edges which correspond to the transverse edges of the vanes, and an edge which is parallel to the generating axis and slides axially as the plane rotates.

9. A rotary fluid displacement machine including a casing having a cylindrical bore and end walls therefor; and a rotor concentrically mounted in the casing and provided with axially sliding vanes which can also move outwardly toward the cylindrical wall of the bore, the end walls of casing having cam surfaces for moving the vanes axially, said vanes and said rotor coacting with said cylindrical wall to provide working chambers at the respective ends of the rotor, the casing having intake and discharge passages for respectively passing fluid into and out of said working chambers during rotational movement of the rotor and during axial movement of the vanes; the vanes each having an edge disposed parallel to the axis of the rotor, and transverse edges, the latter converging relatively toward the cylindrical wall of the bore, said cam surfaces conber; a rotor concentrically mounted in said chamber; and vanes slidably mounted in said rto said cylindrical wall of the chamber and thus compensate automatically for frictional wear and maintain fluid tight sealsalong said parallel llsigned in use to contact corresponding parallel and converging walls of a fluid displacement chamber in a fluid displacement machine under the influence of a force constantly urging said edges into rubbing engagement with the chamber walls, whereby said edges will be automatically compensated for wear and will constantly make a fluid tight seal with said walls. 80 12. A vane for use in a rotary positive fluid displacement machine having a fluid displacement chamber and a rotor concentrically mounted therein, said chamber having a cylindrical curved wall and relatively outwardly converging 85 end walls, said rotor being rotatable relatively with respect to said chamber walls, said vane consisting of a polygonal rigid planar body having at least one edge parallel to the axis of said cylindrical wall and the two edges adjacent thereto 40 corresponding with said converging chamber walls, said parallel and converging edges designed in use to have rubbing contact with said corresponding cylindrical and converging walls respectively and when held in contact therewith 46 adapted to automatically compensate for wear of the contacting parts and provide a constant fluid tight seal along said edges.

13. A vane for use in a rotary positive fluid displacement machine having a fluid displacement chamber, and a rotor concentrically mounted in said chamber, said chamber provided with a cylindrical curved wall and cams at the respective ends of the rotor and concentrically related to the axis or the rotor, said cams'respectively providing surfaces which converge relatively in the direction of the periphery of the rotor, said cams serving to axially reciprocate a fluid displacing vane on the rotor and enable the vane to move relative to said cylindrical wall. 60 comprising a. vane structure having at least one edge parallel to the axis of the cylindrical wall of the chamber and two oppositely disposed relatively converging edges adjacent thereto corresponding with the converging surfaces of the 68' cams, said parallel and converging edges designed in use to have rubbing contact with said corresponding cylindrical wall and said converging camsurfaces respectively and when held in contact therewith adapted to automatically com- 70 pensate for wear ofthe contacting paris and provide a' constant fluid tight seal along said edges.

' ROBERT TALBOT KNAPP. 

